How to Re-Sign a PKCS7 ?

Question

Hello
I want to re-sign a pkcs7
I tryed to merge 2 PKCS7 with each signature
how can I do the job ?
*1/read the info in the PKCS7 allready signed (its a detached signature)*
signedData = new CMSSignedData(
new CMSProcessableFile(file),
new BufferedInputStream( new FileInputStream(filePKCS7)));
*2/ sign a new PKCS7*
CMSSignedDataGenerator signGen = new CMSSignedDataGenerator();
CMSProcessable content = new CMSProcessableFile(file);
addSignerInSignedDataGenerator(signGen, cert, privateKey, sDigestAlgorithm);
signedDataNew = signGen.generate(content, bAttachFile, sProviderName);
with
     public static void addSignerInSignedDataGenerator(
               CMSSignedDataGenerator signGen,
               X509Certificate cert,
               PrivateKey privateKey,
               String sDigestAlgorithm)
     throws CertStoreException, CMSException, InvalidAlgorithmParameterException, NoSuchAlgorithmException,
     NoSuchProviderException
          CertStore certs = generateCertificateStore(cert);
          signGen.addSigner(privateKey, cert, sDigestAlgorithm);
          signGen.addCertificatesAndCRLs(certs);
*3/ try to merge the 2 PKCS7*
how to merge signedDataNew and signedData ?
*4/ store the PKCS7 merged*
signedData.getEncoded();
There another way to do this ?
thanks !
best regards
David KELLER
Edited by: davidkeller on Oct 7, 2008 8:17 AM

Answer 1

I do this and it seems to work
if(filePKCS7 == null || !filePKCS7.exists())
throw new IOException("file signature not exist : " + filePKCS7);
* Append a new signer in the PKCS7
CMSSignedData sp = new CMSSignedData(
new CMSProcessableFile(file),
new BufferedInputStream( new FileInputStream(filePKCS7)));
CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
gen.addSigners(sp.getSignerInfos());
gen.addCertificatesAndCRLs(sp.getCertificatesAndCRLs("Collection", "BC"));
CMSProcessable content = new CMSProcessableFile(file);
addSignerInSignedDataGenerator(gen, cert, privateKey, sDigestAlgorithm);
signedData = gen.generate(content, bAttachFile, sProviderName);
its seems to be ok
date sign : Sun Oct 05 21:36:01 CEST 2008
date sign : Tue Oct 07 18:24:15 CEST 2008
date sign : Tue Oct 07 18:24:25 CEST 2008
verify : true
Is it the best way to do this ?